Denervation is a surgical procedure for blocking a part of nerve paths for various nerves such as sensory nerves and automatic nerves so that stimulation or information is not delivered. The denervation is being used more and more for treatment of several diseases such as arrhythmia, pain relief, plastic surgery or the like.
In particular, as it has been recently reported that the denervation is available for treatment of hypertension, many endeavors are being made to apply the denervation for effective treatment of hypertension.
In case of hypertension, since blood pressure can be mostly controlled with drugs, most hypertensive patients are depending on drugs until now. However, if blood pressure is lowered with drugs, a hypertensive patient should take the drugs continually, which causes inconvenience and increases costs. In addition, if drugs are taken for a long time, various problems such as damage to internal organs or other side effects. Moreover, some hypertensive patients suffer from intractable hypertension which does not allow easy control of blood pressure with drugs. Since the intractable hypertension is not treated with drugs, the possibility of accidents such as a stroke, an irregular heartbeat, a kidney disease or the like increases. Therefore, the treatment of intractable hypertension is a very serious and urgent issue.
In this circumstance, the denervation attracts attention as an innovative scheme to treat hypertension. In particular, the denervation for treating hypertension may be performed by ablating sympathetic nerves around renal nerves, namely the renal artery, to inactivate nerve conduction so that the renal nerves are blocked. If the renal nerve is activated, the production of renin hormone increases by the kidney, which may cause the increase of blood pressure. Therefore, if the renal nerve is blocked, nerve conduction is not performed, and thus the hypertension may be treated, as proven by various recent experiments.
As described above, a representative renal denervation for treating hypertension is using a catheter. In the denervation using a catheter, a catheter is inserted into a part of a human body, for example the thigh, and a distal end of the catheter is located at the renal artery. In this state, heat is generated at the distal end of the catheter by means of radio frequency (RF) energy or the like to block sympathetic nerves around the renal artery.
If the denervation using a catheter is performed, a very small region is cut in a human body in comparison to the denervation using an abdominal operation. Therefore, latent complications or side effects may greatly decrease, and the time taken for treatment or recovery is very short due to local anesthesia. Therefore, the denervation using a catheter is spotlighted as a next-generation hypertension treatment method due to the above advantages.
However, the denervation using a catheter, particularly the denervation for treating hypertension, is not yet sufficiently developed and thus there is much room for improvement.
In particular, some of catheters which have been proposed for treating denervation include only one electrode to emit energy such as high frequency, and the electrode is located in a blood vessel, for example in the renal artery to block nerves around the blood vessel. However, in this configuration, the electrode may not be positioned at a proper location of the renal nerve, and thus the renal nerve may not be properly blocked. Therefore, in case of such a catheter, the electrode should be located at various locations of the renal artery in order to properly block the renal nerve, which may increase the time for operation and also result in complicated operating procedures.
To solve this problem, it has been recently proposed to dispose a plurality of electrodes at a distal end of a catheter. However, if a plurality of electrodes is disposed in this way, the distal end of the catheter where the electrodes are disposed, namely a catheter tip, has a complicated structure and a great size. If the distal end of the catheter increases as mentioned above, the catheter may not easily move along a blood vessel with a small diameter, like the renal artery, and may also damage the inner wall of the blood vessel. Further, at the present, when a catheter is used, in order to protect organs such as blood vessels and allow easy movement of the catheter to a destination, a tube, called a sheath, is located in an organ such as a blood vessel, and then the catheter is moved through the sheath near to a destination. In this case, if the catheter has a great distal end, the catheter may not be easily moved into the sheath, which may make it difficult to the sheath during an operation.
In addition, some of catheters proposed in the past may cause stenosis since a blood vessel may be narrowed at an ablated region, and some of catheters proposed in the past may also be not easily manipulated.
Moreover, some of catheters proposed in the past may not ensure a proper contact between an electrode and a blood vessel. In this case, thermal energy by the electrode reaching the nerve may not be in a sufficient level, which may not properly block the nerve.